Stratified ACO-OFDM Modulation for Simultaneous Transmission of Multiple Frames Both on Even and Odd Subcarriers

Abstract

Different variants of optical orthogonal frequency divisions multiplexing (O-OFDM) have been proposed for intensity modulation/direct detection (IM/DD) based indoor optical wireless communication. Among those schemes, direct current biased optical OFDM (DCO-OFDM) and asymmetrically clipped optical OFDM (ACO-OFDM) are widely adopted variants. These schemes have either reduced spectral or power efficiencies, but the co-existence of both good spectral and power efficiency is vital to tackle the challenge of limited bandwidth and limited optical power constraint scenarios. In this paper, simultaneous transmission of Multiple ACO-OFDM frames on both even and odd subcarriers has been proposed to achieve better spectral and energy efficiencies. The analysis of the theoretical bit error rate (BER) performance of the proposed scheme has been done and compared with the result from Monte Carlo simulation for Additive white Gaussian noise (AWGN) channel environment. A good agreement has been achieved between the theoretical BER bound and the simulated BER from Monte Carlo simulation. The proposed scheme provides better spectral efficiency (SE) compared to ACO-OFDM and equivalent SE compared to DCO-OFDM. In addition, it has shown superior energy efficiency performance than both ACO-OFDM and DCO-OFDM of equal SE.